format string

A string that includes a format specifier for each input along with any additional text that you want to appear in the output. A format specifier is a series of characters, initiated by a %, that indicates how to convert the associated input argument into text.

Each format specifier uses the following general syntax:

% modifiersspecifier

This input accepts a maximum of 255 characters.

Specifiers

Specifier

Definition

x

hexadecimal integer

o

octal integer

b

binary integer

d

signed decimal integer

u

unsigned decimal integer

f

floating-point number with fractional format

e

floating-point number in scientific notation

g

floating-point number in either fractional format (f) or scientific notation (e) depending on the exponent of the number:

f—The exponent is greater than -4 or less than the precision specified

e—exponent is less than -4 or greater than the precision specified

^e or ^g

floating-point number in engineering notation

p

floating-point number in SI notation

T

absolute time, most commonly used to interpret timestamp data

t

relative time, most commonly used to interpret numeric data as elapsed seconds

Modifiers for Numeric Specifiers (x, o, b, d, u, f, e, g, p)

If you use multiple modifiers, they must appear in the following order:

%[-][+][#][0][width][.precision || _significantDigits]specifier

Modifier

Definition

Usage Example

Output for 12345

0

Pads any excess space to the left of a numeric parameter with zeros rather than with spaces to reach minimum width.

%06_2f

012000

+

Includes the sign of the number even when the number is positive.

%+6_2f

+12000

#

Removes zeros at the end of the number.

-

Left justifies the output within its width. If LabVIEW inserts spaces to create the specified width, the spaces appear to the right of the value.

%-6_2f

12000_

width

A number specifying the minimum number of characters that LabVIEW uses in the output. If the value requires fewer characters, LabVIEW pads the output with spaces to meet this width.

This width is not a maximum width. LabVIEW uses as many characters as necessary to output the value without truncating it.

Non-numeric characters, such as a decimal point or negative sign, count toward the total width of an output string.

If width is missing or 0, the output uses only as many characters as necessary to contain the formatted value.

%6f

_12345

width.precision

A number specifying how many digits appear to the right of the decimal point in the output.

If neither .precision nor _significantDigits is present, LabVIEW uses a precision of six digits.

If precision is 0, LabVIEW rounds the value to the nearest whole number.

%6.2f

12345.00

width_significantDigits

A number specifying how many significant digits appear in the output. LabVIEW rounds the data only for display purposes, which does not affect the original data.

You cannot use .precision and _significantDigits together in a single format specifier.

%6_2f

_12000

Modifiers for Time Specifiers (t, T)

Use the following syntax to specify which parts of a time you want to format:

%[-]width <time specifier codes>t

Time Format Code

Definition

Values

%a

abbreviated weekday name. This node returns a numeric value for systems that do not support abbreviated names, such as Chinese and Korean.

Sun - Sat

%A

full weekday name

Sunday - Saturday

%b

abbreviated month name. This node returns a numeric value for systems that do not support abbreviated names, such as Chinese and Korean.

Jan - Dec

%B

full month name

January - December

%c

locale-specific default date and time

%d

day of month

01-31

%H

hour (24-hour clock)

00-23

%I

hour (12-hour clock)

01-12

%j

day number of the year

001-366

%m

month number

01-12

%M

minute

00-59

%p

AM or PM flag

AM or PM

%S

second

00-59

%<digit>u

fractional seconds with <digit> precision

%U

week number of the year, with the first Monday as the first day of the first week

00-53

%w

weekday as a decimal number, with 0 representing Sunday

0-6

%W

week number of the year, with the first Monday as the first day of the first week

00-53

%x

locale-specific date

%.1x

long date format

%.2x

abbreviated long date format. This node returns a numeric value for systems that do not support abbreviated names, such as Chinese and Korean.

%X

locale-specific time

%y

year within century

00-99

%Y

year, including the century

1997, for example

%z

difference between locale time and universal time

HH:MM:SS

%Z

time zone name or abbreviation

Literal text

Literal text

Modifier

Definition

-

Left justifies the output within its width. If LabVIEW inserts spaces to create the specified width, the spaces appear to the right of the value.

width

A number specifying the minimum number of characters that LabVIEW uses in the output. If the value requires fewer characters, LabVIEW pads the output with spaces to meet this width.

This width is not a maximum width. LabVIEW uses as many characters as necessary to output the value without truncating it.

If width is missing or 0, the output uses only as many characters as necessary to contain the formatted value.

Modifiers for the String Specifier (s)

Use the following syntax to format a string:

%[-]width s

Modifier

Definition

-

Left justifies the output within its width. If LabVIEW inserts spaces to create the specified width, the spaces appear to the right of the value.

width

A number specifying the minimum number of characters that LabVIEW uses in the output. If the value requires fewer characters, LabVIEW pads the output with spaces to meet this width.

This width is not a maximum width. LabVIEW uses as many characters as necessary to output the value without truncating it.

If width is missing or 0, the output uses only as many characters as necessary to contain the formatted value.

Modifier for Reordering Inputs

Modifier

Definition

number$

Explicitly specifies which input to use for the containing format specifier. This modifier overrides the default input with the input specified by number.

When you use this modifier, the subsequent format specifiers become associated with the inputs that follow the input specified by number. To avoid confusion, National Instruments recommends using this modifier in all format specifiers if you use it in one.

Modifiers for Overriding Units

Modifier

Definition

{unit}

Overrides the original unit of a VI when you use a function to convert a physical quantity (a value with an associated unit). You must use a compatible unit.

Syntax for Including Literal Characters in a Format String

Most characters outside of a format specifier appear literally in the output. However, you must use special syntax for the following special characters:

Default: A string containing the default format specifier for the data type of each input, separated by spaces

initial string

A string to which this node appends format string in order to form the resulting string.

error in

Error conditions that occur before this node runs. The node responds to this input according to standard error behavior.

Default: no error

input

Input data to be converted to text, as determined by the corresponding format specifier in format string. This node assigns inputs to format specifiers sequentially, such that the first format specifier formats input 1, the second format specifier formats input 2, and so on.

Each input can be a string, path, Boolean, enumerated type, timestamp, or numeric value. You cannot use arrays and clusters with this node.

The number of input parameters must match the number of format specifiers in format string. Furthermore, the data type of each input must be compatible with the associated format specifier. Otherwise, the node returns an error.

resulting string

The concatenation of initial string and the formatted output.

error out

Troubleshooting "Too few/many format specifiers." Error

These errors occur when you wire a string to format string that contains a different number of format specifiers than there are input parameters. To fix this mismatch, either resize the node to display the same number of inputs as format specifiers, or modify the number of format specifiers in format string to match the number of inputs.

Troubleshooting "Format specifier type mismatch." Error

This error occurs when you wire a string to format string that contains at least one format specifier whose data type specifier is incompatible with the data type of the corresponding input parameter. The text of the error specifies which parameter caused the mismatch. To fix this mismatch, you must change either the data type specifier in the relevant format specifier or wire a compatible data type to the relevant input.

Syntax element(s)

input

format string

output

Comments

%g

# modifier

12.00

%#g

12

The node interprets the g specifier as f because the exponent of the input in scientific notation (1) is less than the default precision of 6.

The # modifier omits the six zeroes that would normally appear after the decimal based on the default precision of 6.

12000000

%#g

1.2E+7

The node interprets the g specifier as e because the exponent of the input in scientific notation (7) is greater than the default precision of 6.

The # modifier omits the six zeroes that would normally appear after the decimal based on the default precision of 6.

%d

literal %

12.67

score= %d%%

score= 13%

Because the d specifier produces an integer output, LabVIEW rounds the input to the nearest integer.

%% produces a literal %.

width

precision

literal text

12.67

Temp: %5.1f

Temp: 12.7

The 5 in the format specifier specifies a width of 5, and the 1 specifies the precision, or number of digits to the right of the decimal.

overriding units

12.67 N

%5.3f

12.670 N

The format specifier does not include the unit override syntax ({ }), so the output contains the original unit.

12.67 N

%5.3{mN}f

12670.000 mN

{mN} is compatible with N, so the node makes the appropriate conversion.

12.67 N

%5.3{kg}f

12.670 ?kg

{kg} is not compatible with N, so no conversion occurs, and the output includes a ?.

converting to engineering notation

12.67

%.3e

1.267E+1

Without the ^ modifier, the e specifier places the decimal to the right of the most significant digit.

12.67

%^.3e

12.670E+0

Adding ^ to the format specifier produces an output in which the exponent is a multiple of 3. This determines the placement of the decimal.

%p

precision vs. significant digits

12000000

%.2p

120.00M

Using the decimal point as part of the format specifier impacts the precision, or number of digits after the decimal point n the output.

mega (10^6) is the closest SI prefix to the input value, so the output represents the value as M.

12000000

%_2p

120M

Using the _ modifier specifies the number of significant digits in the output.

mega (10^6) is the closest SI prefix to the input value, so the output represents the value as M.

non-decimal numbers (%x, %o, %b)

padding with zeroes

12

%02x

0C

The 2 in the format specifier causes the output to contain at least 2 characters. The 0 in the format specifier causes 0's to appear as the extra characters required to meet the width.

12

%06o

000014

The 6 in the format specifier causes the output to contain at least 6 characters. The 0 in the format specifier causes 0's to appear as the extra characters required to meet the width.

12

%b

1100

This format specifier omits the width, so the output contains only enough characters to represent the input value as a binary number.

%s

multiple format specifiers

Smith

John

Name: %s, %s.

Name: Smith, John.

The format string must contain two format specifiers because the node accepts two inputs.

variable order

first

second

%s %s

first second

format string does not use the $ specifier, so the function populates the percent codes in input order.

first

second

%2$s %1$s

second first

format string uses the $ specifier to display the inputs in a different order than their input order.

first

second

%1$s %1$s %1$s

first first first

format string uses the $ specifier to display the first input multiple times and ignore the second input.

first

second

%2$s %s

error

The first format specifier uses the second input, which causes the next format specifier to want to use a third input. Because there are only two inputs, the node returns an error.